1. Field of the Invention
This invention relates to a touch-screen display, which may be set on a personal computer, a mobile computer, etc., as a displaying and pointing device, and particularly, this invention relates to a touch-screen display with a function of eliminating an input error caused by a difference between a displayed point and a touched point by an angle of a line of sight.
2. Discussion of the Background
Touch-screen displays have been set on a personal computer, a mobile computer, etc. as a displaying and pointing device. These touch-screen displays have a display apparatus and an invisible touch panel, and the invisible touch panel is set over the display apparatus. In these touch-screen displays, some icons, characters, etc., are displayed on the display apparatus. An operator touches the icons, characters, etc., displayed on the display apparatus, and a touch point is detected and thereby the operator's input is detected. In addition, characters can be input by a handwriting input using an input pen.
FIGS. 8a and 8b show a section view of a touch-screen display. A touch panel 3 is set over a display panel 2, for example a LCD (a liquid crystal display). Because the touch panel 3 is invisible, an operator sees icons, characters, etc., displayed on the display panel 2. In this touch-screen display, when a point just above an icon displayed on the display panel 2 is touched, this icon is selected.
As shown in FIGS. 8a and 8b, a gap G exists between the display panel 2 and the touch panel 3. FIG. 8a shows a case that an operator sees the display panel 2 from just above an icon "A" displayed on the display panel 2. In this case, the icon "A", a point B on the touch panel above the icon "A" and the operator's eyes are all in a line. Therefore, when the operator selects the icon "A", the point B is touched and the icon "A" is selected.
On the other hand, FIG. 8b shows a case that an operator sees the display panel 2 from a point not above the icon "A" displayed on the display panel 2. In this case, the icon "A", point B and the operator's eyes are not all in a line, and instead the icon "A", point B' and the operator's eyes are all in a line. However, the point B' is not located just above the icon "A". Therefore, when the operator selects the icon "A", the point B' is touched, and as a result the icon "A" may not be selected. In addition, in a case of a handwriting input, wrong information may be input.
Japanese Patent Laid-Open No. 5-224816 shows a touch-screen display for preventing the problem just described. This touch-screen display has a two-layer touch panel. In this touch-screen display, first, in operator touches the first layer touch panel. A touching point is displayed and thereby the operator can evaluate a difference between a displayed point and a touched point resulting from any deviation in an angle of a line of sight. Next, the operator touches the second layer touch panel for an input.
The above-mentioned touch-screen display in Japanese Patent Laid-Open No. 5-224816 has some problems. First, the operator has to operate knowing a difference between a displayed point and a touched point resulting from any deviation in an angle of a line of sight at each input, and therefore an operation is complicated. Second, when an operator touches the first layer touch panel knowing a difference between a displayed point and a touched point resulting from any deviation in an angle of a line of sight, by a strong touching by the operator, the second layer touch panel may be inadvertently touched too, and a wrong information may be thereby input. Third, the two-layer touch panel may is expensive.
Japanese Patent Laid-Open No. 7-210317 also shows a touch-screen display, and in this touch-screen display, a touch panel automatically moves according to an angle of tilting of a display panel. Moreover, Japanese Patent Laid-Open No. 7-141109 shows a touch-screen display which has a light-producing device on a handset of a phone and more than one photoreceptor around a display panel. The photoreceptors receive light from the light-producing device on a handset and a position of the handset is detected, and a position of displaying and the touch panel is corrected.
The above-mentioned touch-screen display in Japanese Patent Laid-Open No. 7-210317 is complicated because this touch-screen display has to move the touch panel. Further, the touch-screen display in Japanese Patent Laid-Open No. 7-141109 requires a specialized handset.